Biegral Blog

      先看一个错误的程序：

#include <iostream>
using namespace std;


class Basic
{
public:
	virtual void fun(); 
};

class A : public Basic
{
public:
	void fun()
	{
		cout << "hi" << endl;
	}
};

int main()
{
	A a;
	return 0;
}

        可以修改为：

#include <iostream>
using namespace std;


class Basic
{
public:
	virtual void fun() = 0;  // 纯虚函数
};

class A : public Basic
{
public:
	void fun()
	{
		cout << "hi" << endl;
	}
};

int main()
{
	A a;
	return 0;
}

      或者：

#include <iostream>
using namespace std;


class Basic
{
public:
	virtual void fun()
	{
	}
};

class A : public Basic
{
public:
	void fun()
	{
		cout << "hi" << endl;
	}
};

int main()
{
	A a;
	return 0;
}